Field of the Invention
The present invention relates to a magnetic sensor using a magnetoresistance element, and more particularly, to a magnetic sensor including a resistor array including a plurality of resistive element sections each having a magnetoresistance element.
Description of the Related Art
In recent years, a magnetic sensor using a magnetoresistance (MR) element has been used as a sensor for detecting the position of a movable body (see, for example, JP 63-274817 A, JP 04-160315 A, JP 08-285509 A, and JP 09-016923 A).
Each of the disclosed magnetic sensors is configured such that the output of the magnetic sensor changes when a specific direction component of an external magnetic field generated by, for example, a magnet that is installed in the movable body changes in response to a positional change of the movable body relative to the magnetic sensor. Thus, the specific direction component of the external magnetic field is detected, and thereby the position of the movable body can be detected.
For high accuracy detection of the moving body's position, the specific direction component of the external magnetic field needs to be detected with a high degree of accuracy. For this purpose, measures to improve the linearity of the output signal (voltage) with respect to the input signal (the specific direction component of the external magnetic field) have been taken.
As one of the measures, there is known a method in which the output characteristic curve of the MR element (characteristic curve of the resistance of the MR element with respect to the external magnetic field) is changed by applying an external bias magnetic field to the MR element to improve the linearity in the non-saturation region of the output of the MR element (see, for example, JP 07-092199 A).
The above-described method is a method in which the linearity of the output of the MR element is improved by sacrificing the MR ratio. That is, the linearity of the output and the MR ratio are in a trade-off relation. Therefore, when the linearity of the output of the MR element is improved so that the accuracy of detection of the magnetic field can be improved, the MR ratio is greatly reduced. As a result, the magnetic field detection sensitivity is significantly reduced.